Vinyl-type resins



Patented-idly 25, 1939 PATENT OFFICE VINYL-ma assnvs Arnold Kirkpatrick,Webster Groves, Mm, as-

slgnor to Monsanto Chemical Company, St. Louis, Man, a corporation ofDelaware No 1mm. Application August 1, 1936,

. smu No. sass:

s Claims. (01. zoo-1:),

This invention relates to synthetic vinyl-type resins, includingparticularly those consisting of polymerized vinyl acetals.

One vt the objects of the invention is to improve the quality andespecially the stability of hydrolysis of polymerized vinyl acetate andsub-' sequent condensation with formaldehyde or similar reagents thatpromote acetal formation.

The present invention is based upon the discovery that when a smallproportion of an N- -acylJl-alkyl or aryl cyclohexylamine is added to arain its stability is greatly improved. I have also found that.oi' thisclass of stabilizing agents,

the H-tormyl-N-alkyl cyclohexyiamines are especially desirable asagents. for retarding the development 01' color in resins.

Compounds of this class, for. elianipl, m

iormyl-N-butylcyclohexylamine can be conveniently by alkylatingcyclohexylamine, for example. with an alkyl halide, such as butylchloride and acylating the resulting alkylcyclohexyb fi amine. In thecase of formyl compounds, acyla-. tion may be accomplished by meansoi'iormic acid, asmore completely described hereinbelow. Otherstabilizing agents which may be used in place od N formyiN-n-butylcyclohexylamine u are the N-iormyl derivatives of ll-ethyl N-benayb, and N-phenyl-cyclohexylamines. The

corresponding N-acetyl derivatives of these same compounds are slightlyless effective, since; although they exhibit a remarkable stabilizinger- 4| Iect, it is not possible to use them for stabilizing resins totemperatures as high as those for which the N-iormyl derivatives aresuited. The corresponding dicyclohexyiamine derivatives are alsoeffective as stabilizing agents; hence, it is to be lb understood thatthe expression N-alky mwioheaylamineg includesN-cyclohexyl-cyclohexylamine.

The pro oi'thestabillzingagents whichareaddedtotheresintomotectitiromllbyhataresmalLccnsiderably less than those proportions which would berequired of the same agent to eliect plasticization oi the resin.Usually proportions of less than one partby weight to 100 parts of.resin are satisfactory. 'It has been found. that substantially 5 largerproportions have, in some instances. a tendency to decrease thestabilizing effect; on the other hand, larger quantities function asplasticizers. Thus, in one 'case, 0.5% of stabilizing agent gave agreatly increased stability to one resin but the addition cl 1% of theagent tothesameresinproducedareslnthatwasmuch more stable than theoriginal but not 'as' stable as that containing only 0.5%. Theproportions 01' any particular stabilizing agent of the inveniii tionwhich are to be added to impart maximum stability to any particularresin are best determined by preliminary tests. Such tests are describedhereinhelow.

To incorporate. the stabilizing agent into the go resin or compositionscontaining the resin,: numerous methods can be used. The stabilizingagents of the invention are soluble in and compatible with: alcohols.such "as ethyl and methyl alcohol; esters. such as butyl acetate;ketones, such as acetone and diacetone alcohol: aliphatic and aromatichydrocarbons such as gasoline and benzene: drying oils. such as tung andlinseed oil: chlorinated hydrocarbons, such as ethylene dichloride; andcompatible with the resins herein 39 indicated. The resin can bedissolved, if desired, in a mutual solvent for the resin and for thestabilizing agent and the resulting solution evaporated to recover theresin. the resin is to be used in solution or dispersion, for example.in liquid coating compositions, the 'stabliizins a ent canv'be addeddirectly thereto and either dissolved or dispersed therein. A convenientmeth od oi incorporating the agent is to add it directly to the resinduring preparation or while the resin 40 is in a' fluid condition.However, it the resin is in a hard or extremely viscous condition thedifflculty of incorporating such small proportions of stabilizing agentis evident. The preferred method of the invention in this case consistsin adding to'the resin the stabilizing agent in solution in a volatilesolvent. which solvent may bea solvent or non-solvent for'the resin. andthen mixing and subsequently volatilialng the solvent the resin. Asolvent for the stabilizing 5 agent which is at the same time anon-solvent fortherednispreierred since ltavoidsaposslbility of gellingthe resin. Acetoneis a satisfactory volatile solvent'dilution medium forthe agentsioruseaccordingtotheprocedure and its subsequent expulsionfrom the resin is easily accomplished by heating, the acetone beingrecoverable from the vapors, if desired. This method is especially wellsuited for incorporating the stabilizing agent into resins which are infibrous form, that is, a form resembling cotton or cellulose acetate. Inthis case. the stabilizing agent is dissolved in a large proportion of avolatile solvent for the agent which is also a non-solvent for the resinand the resin is impregnated with the solution and subsequently heatedto expel the solvent.

The resins for which the stabilizing agents of the invention areparticularly applicable are those produced from partially hydrolyzedvinyl acetate polymers which have been condensed with formaldehyde(known under the trade-mark "Formvar) and similar resins made bycondensation with acetaldehyde (known under the trade-mark Alvar"). Suchresins are commonly'known as vinyl acetal polymers or resins. Otherresins for which the stabilizing agents are adapted include thosederived from ethylene oxide and polyvinyl alcohols, all of whichsubstances yield transparent glass-like resins whose values arematerially enhanced by increased stability to light and heat.

The examples which follow describe in greater detail the method ofpracticing the invention and some of the advantages accruing therefrom.

Preparation of N -lormyl-N-n-butylcycloheztylamine To 1300 kg. ofcyclohexylamine maintained at or near the boiling point under a refluxcondenser are added with stirring 200 kg. of normal-butyl chloride atapproximately the rate at which it is taken up in the reaction Ingeneral, this rate is fairly slow, though it may be increased ordecreased in accordance with the degree of agitation or thoroughness ofdistribution of the butyl chloride in the mixture. Gentle refluxing andstirring are maintained for a period of about two and a half hours afterthe completion of the addition of the butyl chloride. The reactionmixture is then cooled until crystals begin to appear, at which point200 kg. of a 50% by weight aqueous solution of sodium hydroxide dilutedwith approximately an equal volume of water are added with stirring toinsure thorough distribution. The mixture is transferred to a suitableseparating device or vessel provided with a bottom outlet, and allowedto separate into layers.

The aqueous layer is drawn off and the residual A oily layer is washedwith a small quantity of dilute sodium hydroxide solution.

The N-n-butylcyclohexylamine is recovered by distillation, most of itappearing in the fraction boiling at about C. at a pressure of 10 mm.(about C. at 100 mm.).

The yields obtained by this process correspond to approximately 15% ofthe theoretical yield from the butyl chloride. Instead of thisprocedure, the butylation oi cyclohexylamine can be efiected in anautoclave under pressure or by other well-known methods.

The butylcyclohexylamine obtained above need not be further purified forthe subsequent formylation. To 155.2 kg. of the compound thus prepared,maintained at a temperature of 60? C. under a reflux condenser,areslowly added, with stirring, 70 kg. of 85% formic acid (approximately30% excess) at such a rate that the heat of the reaction is sumcient tomaintain a gentle reflux. If desired, the acid can be added more rapidlyif the mixture is stirred vigorously and cooled during the additions.After all the acid is added the reflux is maintained by outside heat forabout two hours. The formylated product is distilled directly from themixture, preferably directly without any cooling after the end of thereflux period so as to utilize the heat already present in the mixture.

The N-formyl-N-n-butylcyclohexylamine is a clear, colorless liquid witha boiling point of approximately 108-118" at a pressure of 2 mm.(118-123 at 10 mm).

Heat stability results Varying percentages of the stabilizing agent areincorporated with the resin to be stabilized by any suitable method. Thesamples thus prepared are placed in tubes and heated in an oil bath at apreselected temperature, generally somewhat higher than that to which itis desired to stabilize the resin. The discoloration of the samples isobserved after various periods. By these observations it is possible toconclude which materials are .efiective, the optimum proportions to useand the period at that temperature for which the material can bestabilized.

Typical results of tests with the N-formyl-N- n-butylcyclohexylamineprepared in the example follow:

T0 weighted quantities or a commercial fibrous Formvar resin, much likecellulose acetate in appearance, contained in test tubes, were addedweighted quantities of the N-iormyl-N-n-butylcyclohexylamine dissolvedin an amount of acetone suflicient for just wetting the resin andinsuflicient to cause appreciable gelation thereof. The resin wasthoroughly mixed, the acetone was removed therefrom by slight warming orby means of vacuum or a current of air, and the tubes were then immersedin an oil bath maintained at C. Four samples were testedan unstabilizedresin, a commercially "stabilized" resin, and two resins treated asabove sothat they contained 0.5% and 1%, respectively, of N-formyl-N-n-butylcyclohexylamine. After the resin samples were placed inthe oil bath the temperature thereof was gradually raised during thecourse of an hour from 155 C. to 167 C.

The resins after the hour had the following appearance:

1. Unstabilized Very dark 2. Stabilized byemanuiacturer Light yellow 3.Sample 1 (uhstabilized) with 0.5%

formylbutylcyclohexylamine- No change 4. Sample 1 (unstabilized) with1.0% formylbutylcyclohexylamine Discolored but lighter than 2 C. for onehour followed by an additional periodof heating for one-half hour at C.The results were: i

. 2.. Stabilized by manufacturer" Most darkening 3. Sample 1(unstabilized with 0.5%

formylbutylcyclohexylamlne- Least darkening 5. Sample 1 (unstabllized)with 0.125%

formylbutylcyclohemlamine- Slight darkening The above two series oftests establish the upper and lower limits 01' maximum eflectiveness orthe stabilizing asent and indicate that for auaoss 3 optimumeilectiveness at'the temperatures of the tests approximately 0.5% ofN-iormyl-N-butylcyclohexylamine is to be used.

Although I have described representative em- I bodiments oi my inventionand have shown that N-alkyl substituted cyclohexylamines which areacylated are valuable as stabilizing agents, and have set forthrepresentative embodiments of the principles illustrating my invention.it is to 10 be understood that the invention is not specifically limitedto the exact compositions disclosed, but

rather contemplates known equivalents oi the compositions. Toillustrate: I can use. instead oi cyclohexylamlne in producing mycompounds, 15 the corresponding C-alkyl cyclohexylamines.

Cyclohenlamine is obtained by the hydrogenation of aniline. C-methyicyclohexylamine is obtained in like manner by the hydrogenation oftoluidine. The foregoing and other similar at modifications arecontemplated within the scope oi'the present invention as defined by theappended claims.

What I claim is: l. A plastic composition embodying a polymer- 8! lzedvinyl acetal resin whose color is normally unstable to light and heat,containing unliormly distributed therein a stabilizing inhibitordiscoloration consisting of an N-acyl-N-alkyl-cycmhexylarnine in aproportion not substantially logreaterthanonepartperhundredpartsbyweightoftheresin.

2.Aplastieoompositionapolymerized vinyl acetal resin resulting from thecondensation with formaldehyde 01' a partially bydrolyzed vinyl esterpolymer, the color of which is normally unstable to light and heat, saidresin containing uniformly distributed therein a sta- 5 bilizinginhibitor of discoloration consisting oi anN-acyl-N-alkyl-cyclohexylamine in a proportion not substantially greaterthan one part per hundred parts by weight 01 the resin.

3. A product as defined in claim 1 and further characterized in that theacyl is a. torrnyl group.

4. A composition as defined in claim 2 and further characterized in thatthe acyl is a tormyi group.

53A composition as defined in claim 2 and further characterized in thatthe stabilizing agent is N-formyl-N-n-butylcycloheiwlamine.

6. The method of stabilizing a composition embodying a vinyl acetairesin as its resin component, comprising uniiormly incorporating '9 withsaid composition an N-acyl-N-alkyl cyclohexylamine in a proportion notsubstantially greater than one part per hundred parts by weight 01' theresin. '1. Acompositionasdeiinedinclaimlandturgs ther characterized inthat the stabilizing agent is N-i'ormyl-N-n-butyl-cyclohexylamine.

8. A composition as defined in claim 1 and further characterized in thatthe stabilizing agent is N-tormyl-N-ethyl-cyclohenlamine.

mom xmxrs'mrcx.

CERTIFICATE OF CORRECTION.

Patent No. 2,166,955.

ARNOLD KIRKPATRICK.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,seemnd column, lines 'and3}, for the word "weighted" read weighed; andthat the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 29th day of August, A. D. 1939.

(Seal) Leslie Frazer, Acting Commissioner of Patents.

optimum eilectiveness at'the temperatures of the tests approximately0.5% of N-iormyl-N-butylcyclohexylamine is to be used.

Although I have described representative embodiments oi my invention andhave shown that N-alkyl substituted cyclohexylamines which are acylatedare valuable as stabilizing agents, and

have set forth representative embodiments of the principles illustratingmy invention. it is to be understood that the invention is notspecifically limited to the exact compositions disclosed, but

rather contemplates known equivalents oi the compositions. Toillustrate: I can use. instead oi cyclohexylamlne in producing mycompounds, the corresponding C-alkyl cyclohexylamines. Cyclohenlamine isobtained by the hydrogenation of aniline. C-methyi cyclohexylamine isobtained in like manner by the hydro enation of toluidine. Thei'oregoing and other similar modifications are contemplated within thescope oi'the present invention as defined by the appended claims.

What I claim is:

l. A plastic composition embodying a polymerized vinyl acetal resinwhose color is normally unstable to light and heat, containing uniiormlydistributed therein a stabilizing inhibitor oi discoloration consistingof an N-acyl-N-alkyl-cycmhexylarnine in a proportion not substantiallygreaterthanonepartperhundredpartsby weightoftheresin.

zapiastieoomposltionspolymeb ized vinyl acetal resin resulting from thecondensation with formaldehyde 01' a partially hydrolyzed vinyl esterpolymer, the color of which is normally unstable to light and heat, saidresin containing uniformly distributed therein a stabilizing inhibitorof discoloration consisting oi an N-acyl-N-alkyl-cyclohexylamine in aproportion not substantially greater than one part per hundred parts byweight of the resin.

3. A product as defined in claim 1 and further characterized in that theacyl is a. form! group.

4. A composition as defined in claim 2 and further characterized in thatthe acyl is a tormyi group.

53A composition as defined in claim 2 and further characterized in thatthe stabilizing agent is N-formyl-N-n-butylcycloheiwlamine.

6. The method of stabilizing a composition embodying a vinyl acetairesin as its resin component, comprising uniiormly incorporating withsaid composition an N-acyl-N-alkyl cyclohexylamine in a proportion notsubstantially greater than one part per hundred parts by weight 01' theresin. '1. Acompositionasdeiinedinclaimlandturther characterized in thatthe stabilizing agent is N-i'ormyl-N-n-butyl-cyclohexylamine.

8. A composition as defined in claim 1 and further characterized in thatthe stabilizing agent is N-tormyl-N-ethyl-cyclohenlamine.

mom xmxrs'mrcx.

CERTIFICATE OF CORRECTION.

Patent No. 2,166,955.

ARNOLD KIRKPATRICK. It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionas follows: Page 2, seemnd column, lines 50'and3}, for the word"weighted" read weighed; and that the said Letters Patent should be readwith this correction therein that the same may conform to the record ofthe case in the Patent Office.

Signed and sealed this 29th day of August, A. D. 1939.

(Seal) Leslie Frazer, Acting Commissioner of Patents.

